<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .parent{
            width: 300px;
            height: 300px;
            background-color: #ccc;
            /* 水平居中 */
            margin: 0 auto;
            display:flex;
      
        }
        .parent>div{
            width: 60px;
            height: 60px;

        }
        /* order值越大越靠后 */
       .parent>div:nth-child(2){
        /* flex-grow 默认值为0 将父容器剩余空间划分 */
        flex-grow: 1;
       }
       .parent>div:last-child{
        flex-grow: 2;
       }
    </style>
</head>
<body>
    <div class="parent">
        <div class="div1" style="background-color: red;">弹性元素1</div>
        <div class="div2" style="background-color: green;">弹性元素2</div>
        <div class="div3" style="background-color: blue;">弹性元素3</div>
    </div>
</body>
</html>